You must set apart for the Lord your God every firstborn male born to your herds and flocks. You must not work the firstborn of your bulls or shear the firstborn of your flocks.

In the day he divides his inheritance he must not appoint as firstborn the son of the favorite wife in place of the other wife’s son who is actually the firstborn.

Suppose a man has two wives, one whom he loves more than the other, and they both bear him sons, with the firstborn being the child of the less loved wife.

Then the first son she bears will continue the name of the dead brother, thus preventing his name from being blotted out of Israel.

Rather, he must acknowledge the son of the less loved wife as firstborn and give him the double portion of all he has, for that son is the beginning of his father’s procreative power – to him should go the right of the firstborn.

May the firstborn of his bull bring him honor, and may his horns be those of a wild ox; with them may he gore all peoples, all the far reaches of the earth. They are the ten thousands of Ephraim, and they are the thousands of Manasseh.